The present invention concerns a method and an apparatus for the geo-location of jamming signals. More particularly, but not exclusively, this invention concerns a method of locating a source of a jamming signal capable of disrupting a satellite-based navigation system, a detector for carrying out such a method, and a vehicle including such a detector.
Navigation and geo-location systems that rely on receiving and processing signals from satellites are readily disrupted by low powered and relative inexpensive jamming signal apparatus. Such jamming signal apparatus will typically be ground-based and will generate a signal with one or more components at sufficient power at frequencies that disrupt the correct reception (and isolation) of signals from the satellites. There is therefore a need to cope with such signal jammers.
U.S. Pat. No. 6,300,898 proposes a solution in which three airborne vehicles receive satellite GPS signals and retransmit GPS signals at sufficiently high-power as to defeat jamming by the typical low-power ground-based signal jammers. Such a solution is of course costly and often impractical for many applications, particularly those where speed of response is required.
U.S. Pat. No. 7,233,284 proposes a hand-held jammer locator device. The device operates by detecting a jamming signal with two spatially separated antennae which provide the device with the ability to output information on the strength and direction of the jamming signal. U.S. Pat. No. 7,233,284 discloses manual operation of the device by a user on the ground. No means or method of identifying the exact location of the jammer is explicitly disclosed in U.S. Pat. No. 7,233,284. U.S. Pat. No. 7,233,284 is also reliant on having two antennae to detect the direction from the device at which of the jamming signal source is located.
There are other proposals for GPS jamming location systems, such as the “GOPHER” system developed by SARA (Scientific Applications and Research Associates, Inc.). It is believed that the GOPHER system is one which can operate in a static configuration.
The present invention seeks to mitigate one or more of the above-mentioned problems. Alternatively or additionally, the present invention seeks to provide an improved method of locating a source of a jamming signal capable of disrupting a satellite-based navigation system. Alternatively or additionally, the present invention seeks to provide an improved signal jammer detector.